The present invention relates to a pedal crank/gear assembly for a bicycle, of the type in which the pedal crank is arranged at one end for connection to the spindle of the central drive of the bicycle and carries a series of gears for meshing selectively with the bicycle chain.
FIGS. 1, 2 of the appended drawings illustrate a pedal crank/gear assembly of conventional type. The pedal crank I has a body 2 with a threaded hole 3 in one end for the connection of the pedal and a hole 4 in the other end for the connection of the spindle of the central drive of the bicycle, including a tapered square-section part 5 and a threaded part 6. The said end of the pedal crank I which is arranged for connection to the spindle of the central drive of the bicycle has spokes 7 to whose ends are fixed two gears 9, 10 by bolts 8. More precisely, the gears 9, 10 have flat annular bodies fixed by the bolts 8 to the two opposing faces of the ends of the spokes 7. A third gear Il of smaller diameter than that of the gear 10 which latter in turn has a smaller diameter than that of the gear 9, also has a flat annular body and is fixed by screws 12 to bosses 13 constituted by members separate from the pedal crank body 2, and having end spigots 13a (FIG. 1) screwed into corresponding threaded holes of the spokes 7.
The type of assembly described above does not enable gears having a diameter or a number of teeth less than a predetermined value to be connected to the pedal crank. This opposes the recent tendency to reduce the diameter of the gears on the central drive and of the sprockets on the hub of the rear wheel of the bicycle, for a given transmission ratio, in order to lighten the bicycle itself. This tendency is obviously particularly noted in the case of competition bicycles.